Queen: "I Want It All"
I hate it when the carburetor can't keep up with the gas peddle. If going with sealed, sealed will be worse because of the problems of a single subwoofer in a room your size. If going single with a sealed subwoofer, my recommendation would be to consider an XS30.
If wanting a single vented subwoofer, consider a XV30 or a XV30f.
No cabin gain in 12' W X 21' D X 8' H room? anyway we not there yet, let's dial this baby in first.